Camera lens

ABSTRACT

A camera lens is disclosed. The camera lens includes four piece ultra-thin and wide angle lenses with excellent optical properties and with chromatic aberration sufficiently corrected as follows: a first lens with positive refractive power; a second lens with negative refractive power; a third lens with positive refractive power; a fourth lens with negative refractive power; which are arranged sequentially from object side. The camera lens is characterized in that it meets specified conditions.

FIELD OF THE INVENTION

The present invention relates to a camera lens, and more particularly toa camera lens very suitable for mobile phone camera module and WEBcamera lens etc. equipped with high-pixel camera elements such as CCD,CMOS etc.

DESCRIPTION OF RELATED ART

In recent years, various camera devices equipped with camera elementssuch as CCD, CMOS are extensively popular. Along with development oncamera lens toward miniaturization and high performance, ultra-thin andhigh-luminous flux (Fno) wide angle camera lenses with excellent opticalproperties are needed.

The technology related to the camera lens composed of four pieceultra-thin and high-luminous flux (Fno) wide angle lenses with excellentoptical properties is developed gradually. The camera lens mentioned inthe proposal is composed of four piece lenses which are arrangedsequentially from object side as follows: a first lens with positiverefractive power; a second lens with negative refractive power; a thirdlens with positive refractive power; a fourth lens with negativerefractive power.

The camera lens disclosed in embodiments 1˜2 of the patent document 1 iscomposed of four lenses mentioned above, but refractive powerdistribution of the first lens and the fourth lens is insufficient andshape of the first lens and the second lens is improper; so TTL/LH≧1.68it is not sufficiently ultra-thin.

The camera lens disclosed in embodiments 1˜4 of the prior referencedocument 2 is composed of above mentioned four piece lenses, but theshape of the second lens is improper; therefore Fno=2.4 brightness isnot sufficient.

PRIOR REFERENCE DOCUMENTS

[Prior Reference Document 1] Japan Patent No. JP5815907;

[Prior Reference Document 2] Japan Patent No. JP5667323.

Therefore, it is necessary to provide a novel camera lens to solve theabove-mentioned technical problem.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present disclosure. Moreover,in the drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is an illustrative structure of a camera lens LA of the presentdisclosure.

FIG. 2 is an illustrative structure of a camera lens LA in accordancewith a first embodiment (Embodiment 1) of the present disclosure.

FIG. 3 is a Longitudinal Aberration diagram of the camera lens LA in theEmbodiment 1.

FIG. 4 is a Lateral Color Aberration diagram of the camera lens LA inthe Embodiment 1.

FIG. 5 is a Field Curvature Distortion of the camera lens LA in theEmbodiment 1.

FIG. 6 is an illustrative structure of a camera lens LA in accordancewith a second embodiment (Embodiment 2) of the present disclosure.

FIG. 7 is a Longitudinal Aberration diagram of the camera lens LA in theEmbodiment 2.

FIG. 8 is the Lateral Color Aberration diagram of the camera lens LA inthe Embodiment 2.

FIG. 9 is a Field Curvature Distortion of the camera lens LA in theEmbodiment 2.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention will hereinafter be described in detail withreference to exemplary embodiments. To make the technical problems to besolved, technical solutions and beneficial effects of present disclosuremore apparent, the present disclosure is described in further detailtogether with the figures and the embodiments. It should be understoodthe specific embodiments described hereby is only to explain thisdisclosure, not intended to limit this disclosure.

A camera lens LA in accordance with an embodiment of the presentdisclosure includes, in an order from an object side to an image side, afirst lens L1, a second lens L2, a third lens L3, a fourth lens L4. Aglass plate GF is arranged between the fourth lens L4 and imagingsurface. And a glass cover or an optical filter having the function offiltering IR can serve as the glass plate GF. Moreover, it shall be OKif no glass plate GF is arranged between the fourth lens L4 and theimaging surface.

The first lens L1 has positive refractive power; the second lens L2 hasnegative refractive power; the third lens L3 has positive refractivepower; the fourth lens L4 has negative refractive power. Moreover, thesurfaces of the four lenses should be designed as the spherical shapepreferably in order to correct the aberration well.

The camera lens LA satisfies the following conditions (1)˜(5):1.10≦f1/f≦1.20  (1)−0.55≦f4/f≦−0.30  (2)−2.00≦(R1+R2)/(R1−R2)≦−1.25  (3)1.50≦(R5+R6)/(R5−R6)≦3.00  (4)1.45≦(R7+R8)/(R7−R8)≦3.00  (5); where,f: overall focal distance of the camera lens;f1: focal distance of the first lens L1;f4: focal distance of the fourth lens L4;R1: curvature radius of the first lens L1's object side surface;R2: curvature radius of the first lens L1's image side surface;R5: curvature radius of the third lens L3's object side surface;R6: curvature radius of the third lens L3's image side surface;R7: curvature radius of the fourth lens L4's object side surface;R8: curvature radius of the fourth lens L4's image side surface.

Positive refractive power of the first lens L1 is specified in thecondition (1). It is difficult for development of wide angle trend andaberration correction when the numerical range exceeds the lower limitspecified in the condition (1) because the positive refractive power ofthe first lens becomes too strong; on the contrary, when the numericalrange exceeds the upper limit specified, the development of ultra-thintrend cannot be implemented easily because positive refractive power ofthe first lens becomes too weak.

Therefore, numerical range of condition (1) should be set within thenumerical range of the following condition (1-A) preferably,1.11≦f1/f≦1.20  (1-A)

Negative refractive power of the fourth lens L4 is specified in thecondition (2). The development of ultra-thin and wide angle Fno≦2.2trend cannot be implemented easily outside the range of the condition(2).

Therefore, numerical range of condition (2) should be set within thenumerical range of the following condition (2-A) preferably,−0.53≦f4/f≦−0.45  (2-A)

The shape of the first lens L1 is specified in the condition (3). Thedevelopment of ultra-thin and wide angle Fno≦2.2 trend cannot beimplemented easily outside the range of the condition (3).

Therefore, numerical range of condition (3) should be set within thenumerical range of the following condition (3-A) preferably,−1.45≦(R1+R2)/(R1−R2)≦−1.30  (3-A)

The shape of the third lens L3 is specified in the condition (4). Thedevelopment of ultra-thin and wide angle Fno≦2.2 trend cannot beimplemented easily outside the range of the condition (4).

Therefore, numerical range of condition (4) should be set within thenumerical range of the following condition (4-A) preferably,1.70≦(R5+R6)/(R5−R6)≦2.20  (4-A)

The shape of the fourth lens L4 is specified in the condition (5). Thedevelopment of ultra-thin and wide angle Fno≦2.2 trend cannot beimplemented easily outside the range of the condition (5).

Therefore, numerical range of condition (5) should be set within thenumerical range of the following condition (5-A) preferably,1.55≦(R7+R8)/(R7−R8)≦2.00  (5-A)

The third lens L3 has positive refractive power and meets followingcondition (6).0.40≦f3/f≦0.50  (6); where,f: overall focal distance of the camera lens;f3: focal distance of the third lens L3.

The positive refractive power of the third lens L3 is specified in thecondition (6). When the numerical range exceeds the lower limitspecified, the positive refractive power of the third lens becomes toostrong; the image surface can change greatly because of high orderaberration or axial core shift of the third lens. On the contrary, whenthe numerical range exceeds the upper limit specified, the developmentof ultra-thin trend cannot be implemented easily because positiverefractive power of the third lens becomes too weak.

Therefore, numerical range of condition (6) should be set within thenumerical range of the following condition (6-A) preferably,0.44≦f3/f≦0.49  (6-A)

Because four lenses of camera Lens all have the stated formation andmeet all the conditions, so it is possible to produce a camera lenswhich is composed of four lenses with excellent optional properties, TTL(optical length)/IH (image height)≦1.50, ultrathin, wide angle 2ω≧80°,Fno≦2.2

The camera lens LA of the invention shall be explained below by usingthe embodiments. Moreover, the symbols used in all embodiments are shownas follows. And mm shall be taken as the units of the distance, theradius and the center thickness.

f: overall focal distance of the camera lens LA

f1: focal distance of the first lens L1

f2: focal distance of the second lens L2

f3: focal distance of the third lens L3

f4: focal distance of the fourth lens L4

Fno: F value

2ω: total angle of view

S1: aperture

R: curvature radius of optical surface, central curvature radius whenthe lens is involved

R1: curvature radius of the first lens L1's object side surface

R2: curvature radius of the first lens L1's image side surface

R3: curvature radius of the second lens L2's object side surface

R4: curvature radius of the second lens L2's image side surface

R5: curvature radius of the third lens L3's object side surface

R6: curvature radius of the third lens L3's image side surface

R7: curvature radius of the fourth lens L4's object side surface

R8: curvature radius of the fourth lens L4's image side surface

R9: curvature radius of the glass plate GF's object side surface

R10: curvature radius of the glass plate GF's image side surface

d: center thickness of lenses or the distance between lenses

d0: axial distance from the open aperture S1 to the object side surfaceof the first lens L1

d1: center thickness of the first lens L1

d2: axial distance from the image side surface of the first lens L1 tothe object side surface of the second lens L2

d3: center thickness of the second lens L2

d4: axial distance from the image side surface of the second lens L2 tothe object side surface of the third lens L3

d5: center thickness of the third lens L3

d6: axial distance from the image side surface of the third lens L3 tothe object side surface of the fourth lens L4

d7: center thickness of the fourth lens L4

d8: axial distance from the image side surface of the fourth lens L4 tothe object side surface of the glass plate GF

d9: center thickness of the glass plate GF

d10: axial distance from the image side surface to the imaging surfaceof the glass plate GF

nd: refractive power of line d

nd1: refractive power of line d of the first lens L1

nd2: refractive power of line d of the second lens L2

nd3: refractive power of line d of the third lens L3

nd4: refractive power of line d of the fourth lens L4

nd5: refractive power of line d of the glass plate GF

vd: abbe number

v1: abbe number of the first lens L1

v2: abbe number of the second lens L2

v3: abbe number of the third lens L3

v4: abbe number of the fourth lens L4

v5: abbe number of the glass plate GF

TTL: optical length (axial distance from object side surface to theimaging surface of the first lens L1)

LB: axial distance (including thickness of the glass plate GF) from theimage side surface to the imaging surface of the fourth lens L4;

IH: image heighty=(×2/R)/[1+{1−(k+1)(×2/R2)}½]+A4×4+A6×6+A8×8+A10×10+A12×12+A14×14+A16×16  (7);

-   -   wherein R indicates the curvature radius on the axle; k        indicates the conic coefficient; and A4, A6, A8, A10, A12, A14        and A16 indicates the coefficients of the aspheric surface

For convenience sake, the aspheric surface shown in the formula (7)shall be taken as the aspheric surfaces of all lens surfaces. However,the invention shall be not limited to the polynomial form of theaspheric surface shown in the formula (7).

Embodiment 1

The configuration structure diagram of the camera lens LA in theEmbodiment 1 is shown in the FIG. 2. Moreover, the data includingcurvature radius R of the object side surfaces and the image sidesurfaces of L1˜L4, center thicknesses of the lenses, the distances damong the lenses, refractive powers nd and abbe numbers v d of the lensL1-L4 in the Embodiment 1 are shown in the Table 1, wherein the cameralens LA is formed by the lens L1˜L4; and the data including coniccoefficients k and aspheric coefficients are shown in the Table 2.

TABLE 1 R d nd v d S1 ∞ d0= −0.085 R1 1.33786 d1= 0.474 n1 1.544 v 156.1 R2 9.13441 d2= 0.188 R3 −7.13861 d3= 0.310 n2 1.651 v 2 21.5 R414.25978 d4= 0.231 R5 −1.89878 d5= 0.600 n3 1.544 v 3 56.1 R6 −0.52379d6= 0.060 R7 1.59535 d7= 0.282 n4 1.535 v 4 56.1 R8 0.44437 d8= 0.630 R9∞ d9= 0.210 n5 1.517 v 5 64.2  R10 ∞  d10= 0.336

TABLE 2 conic coefficient aspheric coefficient k A4 A6 A8 A10 A12 A14A16 R1 −3.22E+00 1.01E−01 6.88E−02 −7.14E−01 4.56E−01 7.35E−01 −1.67E+012.71E+01 R2 0.00E+00 −2.98E−01 −4.67E−01 −1.70E−04 −1.47E+00 −1.18E+004.37E+00 6.65E+00 R3 1.04E+02 −4.67E−01 −3.90E−01 −8.25E−01 9.84E−014.19E+00 4.31E+00 −1.28E+00 R4 0.00E+00 −2.61E−02 −2.86E−01 1.08E−015.62E−01 1.08E−01 −1.60E−01 1.36E−02 R5 −1.14E+01 1.85E−01 −4.95E−02−1.25E−01 −1.06E−01 1.45E−01 2.64E−01 −2.96E−01 R6 −3.70E+00 −2.05E−011.73E−01 7.51E−02 1.10E−02 −2.81E−02 −3.39E−02 1.33E−02 R7 −4.80E+00−2.59E−01 6.02E−02 1.46E−02 −1.57E−03 −1.39E−03 −1.87E−04 1.11E−04 R8−4.35E+00 −1.52E−01 5.66E−02 −1.45E−02 7.04E−04 3.58E−04 −3.62E−05−9.87E−07

The values in the embodiments 1 and 2 and the values corresponding tothe parameters specified in the conditions (1)-(6) are shown in thesubsequent Table 5.

The Embodiment 1 meets the conditions (1)-(6), as shown in Table 5.

See FIG. 3 for Longitudinal Aberration of the camera lens LA in theEmbodiment 1, see FIG. 4 for Lateral Color Aberration of it, and seeFIG. 5 for curvature of field and distortion of it. Further, thecurvature of field S in the FIG. 5 is the one in the sagittal direction,and T is the one in the direction of meridian, as well as in theEmbodiment 2. Moreover, the camera lens LA in the embodiment 1 involvesthe ultra-thin wide angle camera lens having high luminous flux as shownin FIGS. 3-5, wherein 2ω=86.6°, TTL/IH=1.446, Fno=2.19; therefore, it isno wonder that this lens has these excellent optical properties.

Embodiment 2

The configuration structure diagram of the camera lens LA in theEmbodiment 2 is shown in FIG. 6. Moreover, the curvature radius R of theobject side surfaces and the image side surfaces, the center thicknessesof the lenses, the distances d among the lenses, the refractive powersnd and abbe numbers vd of the lens L1-L4 in the Embodiment 2 are shownin the Table 3, wherein the camera lens LA is formed by the lens L1-L4;and the conic coefficients k and aspheric coefficients are shown in theTable 4.

TABLE 3 R d nd v d S1 ∞ d0= −0.085 R1 1.34143 d1= 0.476 n1 1.544 v 156.1 R2 9.33181 d2= 0.189 R3 −7.15029 d3= 0.309 n2 1.640 v 2 23.5 R414.06718 d4= 0.230 R5 −1.90117 d5= 0.599 n3 1.544 v 3 56.1 R6 −0.52406d6= 0.061 R7 1.59691 d7= 0.282 n4 1.535 v 4 56.1 R8 0.44396 d8= 0.630 R9∞ d9= 0.210 n5 1.517 v 5 64.2  R10 ∞  d10= 0.319

TABLE 4 conic coefficient aspheric coefficient k A4 A6 A8 A10 A12 A14A16 R1 −3.18E+00 1.02E−01 6.78E−02 −7.18E−01 4.40E−01 6.68E−01 −1.69E+012.65E+01 R2 0.00E+00 −2.97E−01 −4.67E−01 3.08E−03 −1.46E+00 −1.16E+004.37E+00 6.52E+00 R3 1.04E+02 −4.70E−01 −3.96E−01 −8.32E−01 9.80E−014.20E+00 4.37E+00 −1.09E+00 R4 0.00E+00 −2.51E−02 −2.85E−01 1.09E−015.63E−01 1.08E−01 −1.59E−01 1.84E−02 R5 −1.14E+01 1.85E−01 −4.93E−02−1.24E−01 −1.05E−01 1.45E−01 2.64E−01 −2.95E−01 R6 −3.69E+00 −2.05E−011.73E−01 7.50E−02 1.09E−02 −2.82E−02 −3.39E−02 1.34E−02 R7 −4.81E+00−2.59E−01 6.02E−02 1.46E−02 −1.57E−03 −1.38E−03 −1.86E−04 1.11E−04 R8−4.33E+00 −1.52E−01 5.66E−02 −1.45E−02 7.02E−04 3.58E−04 −3.63E−05−1.02E−06

The Embodiment 2 meets the conditions (1)-(6), as shown in Table 5.

See FIG. 7 for Longitudinal Aberration of the camera lens LA in theEmbodiment 2, see FIG. 8 for Lateral Color Aberration of it, and seeFIG. 9 for curvature of field and distortion of it. Moreover, the totalangle of view is involved in the camera lens LA in the Embodiment 2 asshown in FIGS. 7-9, and the lens refers to the ultra-thin wide anglecamera lens having high luminous flux, wherein 2ω=87.0°, TTL/IH=1.439,Fno=2.19; therefore, it is no wonder that this lens has these excellentoptical properties.

The values in all embodiments and the values corresponding to theparameters specified in the conditions (1)-(6) are shown in the Table 5.Moreover, the units including 2ω(°), f (mm), f1 (mm), f2 (mm), f3 (mm),f4 (mm), TTL (mm), LB (mm) and IH (mm) are shown in the Table 5,respectively.

TABLE 5 Embodiment 1 Embodiment 2 Condition f1/f 1.170 1.173 1 f4/f−0.522 −0.522 2 (R1 + R2)/ −1.343 −1.336 3 (R1 − R2) (R5 + R6)/ 1.7621.761 4 (R5 − R6) (R7 + R8)/ 1.772 1.770 5 (R7 − R8) f3/f 0.478 0.480 6Fno 2.19 2.19 2ω 86.6 87.0 f 2.410 2.404 f1 2.820 2.820 f2 −7.267 −7.369f3 1.152 1.153 f4 −1.258 −1.256 TTL 3.321 3.305 LB 1.176 1.159 IH 2.2972.297 TTL/IH 1.446 1.439

It is to be understood, however, that even though numerouscharacteristics and advantages of the present exemplary embodiments havebeen set forth in the foregoing description, together with details ofthe structures and functions of the embodiments, the disclosure isillustrative only, and changes may be made in detail, especially inmatters of shape, size, and arrangement of parts within the principlesof the invention to the full extent indicated by the broad generalmeaning of the terms where the appended claims are expressed.

What is claimed is:
 1. A camera lens comprising, in an order from anobject side to an image side: a first lens with positive refractivepower; a second lens with negative refractive power; a third lens withpositive refractive power; a fourth lens with negative refractive power;wherein the camera lens satisfies the following conditions (1)˜(5):1.10≦f1/f≦1.20  (1);−0.55≦f4/f≦−0.30  (2);−2.00≦(R1+R2)/(R1−R2)≦−1.25  (3);1.50≦(R5+R6)/(R5−R6)≦3.00  (4);1.45≦(R7+R8)/(R7−R8)≦3.00  (5); where, f: overall focal distance of thecamera lens; f1: focal distance of the first lens; f4: focal distance ofthe fourth lens; R1: curvature radius of the first lens' object sidesurface; R2: curvature radius of the first lens' image side surface; R5:curvature radius of the third lens' object side surface; R6: curvatureradius of the third lens' image side surface; R7: curvature radius ofthe fourth lens' object side surface; R8: curvature radius of the fourthlens' image side surface.
 2. The camera lens as described in claim 1further satisfying the following condition (6):0.40≦f3/f≦0.50  (6); where, f: overall focal distance of the cameralens; f3: focal distance of the third lens.